As can be seen in the tree in Figure 14.5, extraction of PP complements is very similar to extraction of NP complements from the same positions.
The PP extraction trees differ from NP extraction trees in having a PP
rather than an NP left daughter node under Sq and in having the
fill a PP rather than an NP position in the VP. In other
respects these PP extraction structures behave like the NP extractions,
including being used for topicalization.